I have a 77 Cj7 with a 304. Just rebuilt the motor on it. When it runs, oil is coming out of the dipstick. I did put a pcv valve that I got from Autozone on but it seems like it's just a big black plastic tube that's hollow in the middle. Also, is it suppose to connect to the port at the bottom of the carb in the back? I unhooked the pcv and didn't feel too much vacuum pulling from the intake and the motor runs fine. Actually oil doesn't come out of the dipstick when I don't hook up the pcv. Is that normal for these motors? Also, the oil filler cap has a port with a hose on it. Is that suppose to hook up to the bottom of the air cleaner. I have an aftermarket Holley round air filter and I believe there's a port for a hose underneath. The previous didn't have any of these hoses hooked up so I am trying to figure them out.

You probaley know this, but I don't know if you know. The location of the PCV on the 304? And it does go to one of the larger ports on the carb. There should be enough vaccume, that when unplugged, the engine wants to stop running. You are correct about the oil fill cap vent, this were the fresh air is drawn into the engine.
The only reason for oil to come out the tube, is internal pressure in the crankcase,

Yes I know the pcv has a grommet and it goes in the middle back of the intake on a 304. The one I got from Autozone is not like a regular one. It's just a hollow tube seems like and it is big also 3/4 inch. Does anyone have a part number of the one for a 304? Thanks.

Yes because the hose is new and the pcv that autozone sold me seems hollow in the middle.He had the other end of it in the oil filler cap that's why there wasn't any vacuum to vent the pressure in the engine.